Evaluation of moxifloxacin and levofloxacin against S. pyogenes in various animal models

Abstract number: 1732_123

Endermann R., Ehlert K.

Objectives: Group A streptococci are frequently implicated in complicated skin and skin structure infection (cSSSI). Moxifloxacin (MXF) has recently been approved for this indication. In this study, the therapeutic efficacy of MXF or levofloxacin (LFX) against a clinical isolate of S. pyogenes (6A47 wild-type) was investigated. We studied both quinolones in a murine sepsis model and in two cSSSI models: the granuloma pouch and the Gelfoam® implant model.

Methods:Sepsis model: bacteria were suspended in 5% mucin in saline and inoculated intraperitoneally. Antibiotics were given intravenously (i.v.) at 1, 4, 24 and 32 h post-infection (p.i.; 5 animals/group). Survival was monitored for 5 days. Granuloma pouch model: pouches were formed by injecting 5 mL of air and 0.5 mL of 0.1% croton oil in olive oil under the skin of the back. After 72 h, the air was replaced by 1 mL of 0.25% agar in saline. A bacterial suspension (0.5 mL) was injected into the pouch after 48 h. Antibiotics were given i.v. at 0.5, 4, 24 and 32 h p.i. (7 animals/group), and viable counts in exudates were assessed at 48 h.

Gelfoam® model: a collagen piece was implanted under the skin of the back. After 3 days, 50 mL of bacterial suspension was injected into the implant. Antibiotics were given i.v. for 3 days (b.i.d.), starting 2 h p.i. (5 animals/group); implants were removed for bacterial cell counts 24 h after treatment ended.